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gfind missing files

Introduction

The tool gfind_missing_files.sh can be used to find the missing files in a GlusterFS geo-replicated secondary volume. The tool uses a multi-threaded crawler operating on the backend .glusterfs of a brickpath which is passed as one of the parameters to the tool. It does a stat on each entry in the secondary volume mount to check for the presence of a file. The tool uses the aux-gfid-mount thereby avoiding path conversions and potentially saving time.

This tool should be run on every node and each brickpath in a geo-replicated primary volume to find the missing files on the secondary volume.

The script gfind_missing_files.sh is a wrapper script that in turn uses the gcrawler binary to do the backend crawling. The script detects the gfids of the missing files and runs the gfid-to-path conversion script to list out the missing files with their full pathnames.

Usage

bash gfind_missing_files.sh <BRICK_PATH> <SECONDARY_HOST> <SECONDARY_VOL> <OUTFILE>
            BRICK_PATH     -   Full path of the brick
            SECONDARY_HOST -   Hostname of gluster volume
            SECONDARY_VOL  -   Gluster volume name
            OUTFILE        -    Output file which contains gfids of the missing files

The gfid-to-path conversion uses a quicker algorithm for converting gfids to paths and it is possible that in some cases all missing gfids may not be converted to their respective paths.

Example output(126733 missing files)

# ionice -c 2 -n 7 ./gfind_missing_files.sh /bricks/m3 acdc secondary-vol ~/test_results/m3-4.txt
Calling crawler...
Crawl Complete.
gfids of skipped files are available in the file /root/test_results/m3-4.txt
Starting gfid to path conversion
Path names of skipped files are available in the file /root/test_results/m3-4.txt_pathnames
WARNING: Unable to convert some GFIDs to Paths, GFIDs logged to /root/test_results/m3-4.txt_gfids
Use bash gfid_to_path.sh <brick-path> /root/test_results/m3-4.txt_gfids to convert those GFIDs to Path
Total Missing File Count : 126733

In such cases, an additional step is needed to convert those gfids to paths. This can be used as shown below:

bash gfid_to_path.sh <BRICK_PATH> <GFID_FILE>
             BRICK_PATH - Full path of the brick.
             GFID_FILE  - OUTFILE_gfids got from gfind_missing_files.sh

Things to keep in mind when running the tool

  1. Running this tool can result in a crawl of the backend filesystem at each brick which can be intensive. To ensure there is no impact on ongoing I/O on RHS volumes, we recommend that this tool be run at a low I/O scheduling class (best-effort) and priority.

     ionice -c 2 -p <pid of gfind_missing_files.sh>

  2. We do not recommend interrupting the tool when it is running (e.g. by doing CTRL^C). It is better to wait for the tool to finish execution. In case it is interrupted, manually unmount the Slave Volume.

     umount <MOUNT_POINT>